Fast Regulator Tick in Soft Mode (Now Solved!)

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Post by xmexclusive »

Hi Jim

Thanks for that detailed explanation, very useful to understand the detail of your checks. If Mk2 XM H4 ECU's will do for test purposes then I have a small selection of spare ones.

John
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Post by Stempy »

I'm kind of confused now as I thought the valves operated as soon as you switch on the ignition, without the engine running and no system pressure for assistance. Maybe I've got the wrong end of the stick :?
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Post by Sl4yer »

Stempy wrote:I'm kind of confused now as I thought the valves operated as soon as you switch on the ignition, without the engine running and no system pressure for assistance. Maybe I've got the wrong end of the stick :?
You're right, in fact whenever a door is opened, regardless of ignition. Maybe the accumulator supplies the pressure needed :?:

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Post by CitroJim »

Sl4yer wrote:
Stempy wrote:I'm kind of confused now as I thought the valves operated as soon as you switch on the ignition, without the engine running and no system pressure for assistance. Maybe I've got the wrong end of the stick :?
You're right, in fact whenever a door is opened, regardless of ignition. Maybe the accumulator supplies the pressure needed :?:

James

The valves will click and hum when there is no hydraulic pressure preset. What I should have said is that the hydraulic pressure assists the valve in switching into soft mode. I've heard that if the main system pressure is low, due to a bad regulator cutting out too early say, the car will fail to switch reliably into soft mode despite good clicks and hums from the valves.

There have been threads on this in the past, one very, very long one by Bernie as I recall and Xantic has had simialr thoughts about his car not reliably switching to soft mode.

When stopped, there will be very little pressure availble to the hydractive blocks as the pressure comes directly from the security valve and when the engine is stopped and the pump not running, this valve will be closed and therefore isolate the accumulator from the suspension feeds; only the circuit to the brake dosuer is open when the security valve is closed to give all priority to the braking system.
Jim

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Post by Mandrake »

CitroJim wrote:Hi John,

I'll be delving more deeply into this; I've got the bit between my teeth now :D
I'm a bit late to the party in this thread but I'm enjoying reading it, it's a bit like reading a whodunnit :lol:
As the valve shuttles to the soft position, the leakage return is fully shut by a needle extension to the shuttle operating on a ground seat. Wear on this needle and its seat could well arise from neglected, dirty LHM. The way the valve is constructed, it should only ever just spurt a bit of leakage on mode changes as the return is effectively blocked in either mode.
Indeed, it should only spit slightly when it switches.

The electrovalves I've had which have leaked have both only leaked in the soft mode with no leakage in hard mode, and in both cases it seems to be wear on the needle valve taper to blame, pitting on the taper on the pin that is visible under a magnifying glass but not obvious to the naked eye.

If both the needle and the seat are worn/pitted, then the rotational angle of the pin will affect the amount of leakage and since the pin is free to rotate slightly as it transitions, I think that explains the random fluctuations in leakage I observed sometimes when the valve switched.

I have to wonder if the wear is simply a result of years of the pin being hammered back and forth hundreds of times an hour every time you drive the car, with any grit in the oil making it past the filter providing an abrasive for it to hammer against.
Electrically, I studied the waveform on my test ECU carefully. I also calibrated the 'scope to ensure I was seeing the truth. Although the mark:space ratio of the squarewave was considerably more space than mark, it was clean and swinging between 0V and full battery voltage and showing no signs of triangulation (suggesteing a thermal shutdown) or other distortion.
For what it's worth, I think your 25/75 on off ratio mentioned at the beginning of the thread is perfectly normal - although I never put a scope on mine, I did measure the RMS voltage accurately and it was around 3v or slightly less in the pulse mode - which corresponds very closely to a 25% mark space ratio, so I think you may be chasing a non-existant problem there :D

Other models of the ECU may have different mark space ratios however.
Also, I listened carefully and the valves were clicking to soft mode with a loud click, which suggested the combined hydraulic pressure and magnetic field were doing their job to cleanly and fully switch the valve. I oberved, on switching, a big spurt of LHM in my temporary transparent leakage return pipe as expected followed by the steady but heavy flow when the valve was in soft mode. Leakage in hard mode was zero.
Interesting that hard mode leakage is usually nill while soft mode is high isn't it ?

The only reasons I can think of that would explain that one end of the needle valve (the outlet end) wears quickly and the inlet end doesn't is -

1) Any grit in the oil that found it's way into the electrovalve would tend to accumulate at the output/exit end of the valve

2) The 12v pulse that opens the valve is probably much stronger than the spring return which closes it, thus "hammering" the seat at that end of the valve harder than the one on the inlet end..... :?:

Regards,
Simon
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Post by DickieG »

Nice to see you back on here Simon, welcome to the UK its a pity you're so far north as it would be good to meet up at Stratford this weekend.
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Post by CitroJim »

Welcome to dear old Blighty Simon :D

And great to see you in this thread 8) All the while it has been running I was hoping you would :wink:
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Post by xantia_v6 »

Mandrake wrote:I have to wonder if the wear is simply a result of years of the pin being hammered back and forth hundreds of times an hour every time you drive the car,
Maybe the square wave driving the solenoid causes it to vibrate slightly, and this vibration causes the wear?
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Post by CitroJim »

xantia_v6 wrote:
Mandrake wrote:I have to wonder if the wear is simply a result of years of the pin being hammered back and forth hundreds of times an hour every time you drive the car,
Maybe the square wave driving the solenoid causes it to vibrate slightly, and this vibration causes the wear?
Could well be and more than likely a combination of both. I favour the neglected LHM changes and dirt running around in the system for an extended time.

I was surprised to find the car already had non-hydractive corner spheres on it so I reckon it has been a long-standing problem and the fitment of those spheres not that long ago and the bright, sparkly LHM were attempts to fix it.

I wonder if a dose of Hydraflush would be a good idea before I fit new electrovalves?
Jim

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Post by myglaren »

CitroJim wrote: I wonder if a dose of Hydraflush would be a good idea before I fit new electrovalves?
Chicken soup for Xantias?
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Post by addo »

myglaren wrote:Chicken soup for Xantias?
Well, it won't clog the LHM tank filters like kreplach did! :P
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Post by KevMayer »

Very interesting thread this one.

I've had my rear electrovalve apart as you may remember, and, I was puzzled by the combination of components inside.

The mild steel shuttle is pushed forward when the valve switches. This will compress the heavy spring which holds the valve in hard mode. But, the centre pin isn't directly linked to the main shuttle body. I have a theory that it is the weaker spring which pushes the centre spindle forward to seat against the leak return port.

If your spring is weak it may not have enough tension to push the centre spindle forward to seal off the leak return.

I've had my rear electrovalve off again to extend this smaller spring quite a bit more than I did the first time. When I re fitted the electrovalve I had a strange phenomenon of the rear end switching to soft mode but my front end staying in hard mode. When I did a test drive my front was very hard where it had always switched to soft without any problem.

I need to get my front electrovalve off and give the small spring a good stretch. I think that by stretching the small spring on the rear valve I may have cured the leakage from the rear which left my front electrovalve as the weak point in the system which stopped the shuttle of the front hydractive block from moving to the soft position.

I'm pretty sure the centre pin isn't moved forward magnetically when the coil is energised. The weaker spring must push it forward, but if if doesn't push it all the way it may just lift it off the seat, which the high pressure LHM will also do, but not lift it forward enough to push the end in to the leak return seat.

Does this make sense ?
Cheers, Kev

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Post by KevMayer »

Pictures from Mandrake on a previous thread:-

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Electrovalve broken down into parts

Image
Close up on main shuttle body and central pin with small spring
Cheers, Kev

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Post by CitroJim »

Kev,

Excellent :D Thanks for posting that, most valuable indeed..

I've nothing to loose so I'll give the lower springs a tweak and report back!
Jim

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Post by CitroJim »

Success :D :D :D

I'm now measuring soft mode regulator ticks with a calandar :lol:

I had both electrovalves in bits today. The front one came apart and left the valve body in the sphere block.. I used a deep 16mm socket to undo the valve.

Image

Very little LHM spills if you depressurise on low first. You loose more LHM from the leakage return pipe at the front.

It was jolly tricky to remove the innards from there but with care and tweezers, I managed it..

Image

I gave the valve a good clean up and stretched the lower spring as Kev Mayer and Steve (steelcityuk) detailed. I stretched it so that it was as long as the part of the shuttle valve it slides over.

Reassembling the front, in the position, was made more complex by me dropping the spring, shuttle and slug as I was holding it with tweezers but luckily, with the aid of a magnet, I retrieved the bits from the front crossmember!!

The rear was easy. The whole valve came out beautifully. It was a bit of a tricky job to separate it but managed it by holding the base in a 24mm socket clamped in my big vice and undoing the top with the 16mm deep socket. I did not bake it first.

Reassembled, soft mode came up beautifully and a very slow tick. When the pump does eventually cut in, it rus for just the briefest of periods.

However, when I switched off, as soon as the front electrovalve switched to hard after 30s, I had the "filling cistern sound" as LHM rushed up the leakage return :(

Apart again and I found I'd been a bit too keen on the spring stretch and I'd managed to catch the very end and it was sticking out, preventing the valve seating properly in hard mode. A bit of reprofiling and after reassembly, all is now well.

It's hard to see in the the picture (green arrow) but be very careful when stretching not to catch the end of the spring and leave a bit sticking out..

Image

This one was a bit too stretched so I used another spring from a very badly corroded electrovalve I have.

Interestingly, the rear valve, which was on the sphere block I replaced and not the original, was very, very dirty from (presumably) dirty LHM at some time. It cleaned up fine but it may have had sufficient dirt on it's seat to make the problem worse. Electrovales do have a very fine gauze on their bases to keep larger particles out so they must be known to be sensitive to contamination.

Moral is, if you have a hydractive car, change the LHM regularly and hydraflush.
Jim

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